It is increasingly being sought to customize chip cards, not only by the recording,, in a non-volatile memory, of specific information elements relating to the user, but also by the printing, on the external visible part of the card, of specific indications or designs relating to the user.
For example, it is possible to envisage a case where the card contains data elements for the identification of a person while the external surface of the card comprises the name and address of the person, his photograph, corporate identification symbol etc.
The chip cards used in present-day technology have a thickness that cannot be less than about 1 to 2 millimeters, since it is necessary to provide for the thickness of the integrated circuit chip, its coating, the electrical connector that will enable the connection of the chip with a card reader, etc.
It has been observed that this non-negligible thickness raises problems with commonly used printing technologies.
Furthermore, it has been observed that it is extremely desirable to carry out the electrical customization of the chip at the same time as the graphic customization of the external surface of the card, i.e. it is desirable to have a single machine to carry out both types of customization at the same time. This averts the risks of the mixing of information elements, for example the assigning of electrical customization data elements that have nothing to do with the graphic data elements printed on the card.
In the prior art, there are automatic machines made of up two parts: an electrical head used to record electrical data (electrical customizing) and a graphic print head working by heat transfer, from a ribbon, for the graphic customizing of the exterior of the card. A machine such as this is described, for example, in the document EP-A-0 266 926 but, in this case, the graphic customization is done by embossing. Another document EP-A-0 027 886 describes a machine for purely graphic customizing by printing.
In these machines, the print heads comprise, on a plane surface, a line of thermal printing dots (elementary heating dots). These heating dots can be applied to the surface of the card, with the interposition of an inking ribbon between the heating dots and the card. Depending on the dots that are actually heated at the time of the printing, a line of inking dots is transferred thermally from the ribbon to the card. A customized pattern (of designs or written characters) can thus be printed line by line on the card.
However, there is a risk that the contact surface of the thermal print head may not be applied properly against the surface of the card if said card shows defects of planeity. This is why it is necessary, in currently used machines, to provide for the bending of the card at the position of the printing, the bending being done in a direction such that the line of dots of the print head is aligned along a generatrix of the cylinder formed by the bent card, and the convexity of the bend being pointed towards the print head side. This enables the line of dots to be applied accurately along this generatrix to print a line of desired dots; after this, the operation passes to a following printing line, the bent card being shifted with respect to the head in such a way that the print head is always on a generatrix of the cylinder formed by the bent card.
For the chip cards, the thickness of the cards is great enough to make it difficult to obtain this bending without setting up excessive strains in the body of the card. These strains may affect not only the plastic material of the card but also the electrical functions of the card, if only because there is a risk of breakage of internal connections between the chip and the connector used to place it in contact with a card reader.
The mechanical equipment needed to obtain a bending of the card is complicated and hence costly.
Furthermore, this mechanical bending equipment is incompatible with the making of the electrical connections with the chip with a view to the electrical customization of the card. Now, it is sought to carry out the electrical customizing simultaneously with the graphic printing, or immediately before or after, notably before inserting a new card facing the print head.
The mechanical bending system has other drawbacks such as, for example, the fact that it practically rules out the possibility of providing for a structure in which the card enters and comes out by the same orifice of the machine. It is necessary to provide for one entry orifice and one exit orifice. And this entails providing for a special electrical reading head system (a reading head capable of being lowered to carry out the customization and then of being raised to let the card pass through towards the exit).
Finally, it has been observed that it is relatively difficult to control the existing machines in order to give good printing results in certain cases, notably when the inserted cards are already printed (by offset or silk screen printing), which can take place even before customization.